Ted Mittelstaedt wrote:
Then why does Linus think manipulating the VM page table mappings is bad? That is, why does he -really- think it's bad, not the publically-given reason? Is it because Linux is extrordinairly inefficient in page table mappings due to some structural decision that Linus made that cannot be reversed now, that it could never be any good at it? Or is there some other reason?
I can't speak with certainty as to what someone else might think; no doubt Linus is entirely capable of explaining his own position should you wish to inquire, however.... :-)
I think Linus doesn't care much for Zero-copy sockets because for the common case of 1500/1504-byte MTU, you end up wasting at least 60% of a 4096-byte page for each packet, and maybe ?three? times that much if your hardware splits the packet into separate pages for the mbuf header, the packet headers, and the packet data.
I think FreeBSD doesn't enable Zero-copy sockets by default because those are legitimate criticisms, but there is some interest and potential for benefits from them, at least for some other circumstances like jumbo ethernet frames.
-- -Chuck _______________________________________________ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "[EMAIL PROTECTED]"
